Histology: the cell and intro Flashcards
(26 cards)
what is PAS used to stain for
sugars- magenta
What does H&E stand for and what does it stain
Haemotoxylin and Eosin
nuclei- dark blue, cytoplasm/extracellular material- pink, empty space/watery interstitial fluid e.g. glycosaminoglycan matrix - white
What does Van Gieson stain
elastic- black/brown
What does Alcian blue stain
mucins- dark blue
What does trichrome stain
3 difernet stains, stains difefrnet things
Why do cell sizes differ
smaller cells e.g. lymphocytes have to move around the body so muct be smaller they are also less metabolically active so require less organelles - comparitavly motoor neurones stay in fixed place and more metaboillivaly active due to cell signalling
define cuboidal
as tall as it is wide
define squamos and e.g.
flat cells
define columnar and e.g.
taller than wide
define rounded and e.g.
rounded shape but not always spherical (erythrocytes)
define polygonal and e.g.
cells have been squished togetehr and dont have unifrom shape
define fusiform and e.g.
spindle like shape e.g. muscle fibres
What is present at the nucleus
The nucelus holds the genetic informaation of the cell, it has a double membrane with pores in it, the memebrane is often continue with RER, DNA ascoisated with hostones to be called nucleosomethis then toghtly coils more and is called chromatin, nucelolus is presnt and that where ribsomes (rRNA) are produced.
eurchromatin vs heterocharomatin
euchromatin is lighter and is actively transcribed DNA and heterchromatin is darker and transcriptionally inactive and sits close to nuclear memebrane. You can convert between euchromatin and heterchromatoin as a form of gene regulation
Describe the appearnace and function of a mitochondrion
Mitochria contain a double membrane, smotth outer memebrane and highly folded ineer cristae, site of oxidative phosphorylation, conversion of ADP to ATP, has it’s own DNA
What may you see when looking at cells of someone who has taken colchine or a colchine like drugs?
ring mitoses, (due to halt of mitosis at anaphase)
What is 5’ cap and 3’ tail maid from?
5’ cap is made from methylated guanaine and tail is multiple adenine
What causes down syndrome?
Trisomy 21 (three chromosme), due to non-disjunction of chromosomes during meiosis. Typically maternal but ocasionally paternal
What are introns? exons?
introns contain non-coding sequences (IN the bin) and are spliced out of mRNA before leaving nucleus, exons contain coding sequences
example of stop codons
UAA, UAG and UGA
What are tight junctions?
also known as occluding junctions these junctions help create an impermebale barrier between adjacent epithelial cells and form bandlike connections. This forces molcules to move through the cell- this junctions are usefully in cells that active transport to prevent back diffusion. Particulalrly well developed in cells ligning the small bowel.
What are desmosomes?
also known as anchoring junctions these junctions help provide mechanical strength to the epithelial cells. Desmososmes connect adjacent cells cytoskeleton togetehr and hemidesmosomes connect epitheilail cells to extracellular basement memebrane. These are most commonly found in adjacent columnar and cuboidal cells where they link to an ‘adhesion belt’. Also particularly well developed in squamos epithelial cells of skin
What are gap junctions?
also known as communicating junctions, they allow ajacent cell-cell comunications by diffusion of molceules. They are musch more common during embryogenesis when they allow communication for spatial organisation of cells. Also important in cardiac and muscle cells.
microvilli contain actin filaments to help keep shape of microvilli, help incraese SA so are typically a specialisation on absorption of secretory columnar or cuboidal epithelial cells.
